Method of storing titanium sponge



Unite tates Patent )Ofli e 2,841,487 Patented July 1, 1958 METHOD OF STORING TITANIUM SPONGE Alexandre R. Tarsey, Las Vegas, and Delmar B. Davis,

Henderson, Nev., assignors to Titanium Metals Corporation of America, New York, N. Y., a corporation of Delaware No Drawing. Application April 3!), 1956 Serial No. 581,304

3 Claims. (Cl. 75-345) This invention relates to the storage of titanium metal sponge, and more particularly to the storage of such sponge containing magnesium chloride as an impurity.

Titanium metal sponge is commonly produced by reaction of titanium tetrachloride and metallic magnesium according to the so-called Kroll process. The product is a spongy porous mass, which may be in various states of subdivision, and inevitably contains some magnesium chloride as a by-product impurity which is substantially impossible to remove completely by commonly practiced techniques. In the presence of moisture, even that present in relatively dry air, magnesium chloride, which is hygroscopic, forms a hydrated compound. When sponge containing such hydrated magnesium chloride is heated as in melting to form ingots, the hydrated magnesium chloride does not release all its added water but may in part decompose to form HCl and magnesium hydroxychloride or some other magnesium-oxy compound. The hydroxychloride or whatever magnesium oxide-containing compound is eventually formed is not removed, and its oxygen content seriously afiects the quality of the resulting titanium metal by increasing its hardness.

Storage of titanium sponge without deleterious efiects on its quality cannot generally be successfully accomplished by providing a surrounding atmosphere in which is provided any of the commonly employed desiccants. Magnesium chloride is itself a powerful desiccant and competes actively for any moisture present. The employment of hermetically sealed containers flooded with an inert gas, or evacuated, is not practicable on a large scale, and the cost involved would be prohibitive.

This invention has for its principal object provision of an improved method for storing titanium sponge containing magnesium chloride impurity. A further object is to provide a method for storing such sponge which is simple and effective in preserving its quality. These and other objects of this invention will be apparent from the following detailed description thereof.

This invention, in its broadest aspects, contemplates the storage of titanium sponge which'contains magnesium chloride impurity, in a closed container in the presence of anhydrous aluminum chloride.

The containers employed in the practice of this invention are essentially formed of impervious material, preferably metal, and should be provided with closures that enable the containers to be tightly closed. It is a feature of this invention, however, that containers which can provide hermetic sealing are not necessary, and the type of closure recognized as being reasonably gas tight and leak proof will be adequate. Standard metal drums which have a tight fitting gasket cover are preferred if the sponge is to be stored in comparatively small unit quantities. If bins or silos are employed, the closures should be designed for approximately equivalent etfect. Other forms of containers such as bags and barrels may be used if the material of construction is suitably resistant to the passage of air and water vapor, and the closure is tight as defined above.

The aluminum chloride preferably is-arranged in the presence ofthe sponge by placing it inside the container with the sponge, preferably enclosed in a porous container which may, for'example, be fabricated from cloth, paper or other gas porous material. Placing the aluminum chloride "in direct'contact with the sponge is effective, 'bjut is disadvantageous .in.that it must be'. carefully separated .after storage .to .preventicon'tamina'tion 'of ithe sponge thereby.' A convenient and advantageous procedure is to almostfill the container with sponge granules, place a porous paper bag containing anhydrous aluminum chloride on top of the sponge, and then tightly closing the container. The amount of aluminum chloride employed may vary widely. Generally about 0.25 pound to about 1 pound per 100 pounds of sponge is required. Up to 5 pounds per 100 pounds may be employed, although the excess does not ordinarily improve results.

The beneficial elfect of storage of titanium sponge, according to this invention, depends, apparently, on the unique properties of anhydrous aluminum chloride which, in addition to being an effective desiccant, slowly decomposes, releasing hydrogen chloride. Its action in the container is apparently to condition the atmosphere in which the sponge is stored by absorbing water and providing in such atmosphere an appreciable percentage of HCl gas. Magnesium chloride impurity which may be present in amount from 0.01% to 0.5% or occasionally more will not absorb moisture to form a hydrated salt or a hydroxychloride compound, but will remain as magnesium chloride in which state it is relatively harmless to the titanium metal quality. Actually the reaction involved may go further and reform magnesium chloride which may have been converted to magnesium hydroxychloride during previous processing or handling. Thus an improvement in the quality of the sponge may result, particularly where high hardness in.the original sponge is caused by excessive content of magnesium hydroxychloride impurity.

The following example illustrates the practice of an embodiment of this invention.

Example 1 A standard steel drum of gallons capacity was filled to within about an inch of the top with 450 pounds of titanium metal sponge granules containing 0.15% MgCl and having a Brinell hardness number of 168.

A porous paper bag containing 2.5 pounds of anhydrous aluminum chloride was placed on top of the sponge, and the cover, which was provided with a rubber gasket, was placed on the drum and clamped tight. After four months storage the drum was opened and hardness determination on the sponge showed a Brinell hardness number of 166, which was about the same as before storage.

Another portion of the same sponge stored in an identical drum under the same conditions without aluminum chloride showed on opening an increased Brinell hardness number of 175.

The method of this invention provides for economical storage of titanium sponge containing magnesium chloride impurity under conditions such that the quality of the sponge, as measured by the Brinell hardness number, thereof is not adversely affected.

I claim:

1. A method for storing titanium metal sponge which contains magnesium chloride impurity which comprises storing said sponge in a closed container in an atmosphere conditioned by the presence of aluminum chloride.

2. A method for storing titanium metal sponge which contains magnesium chloride impurity which comprises storing said sponge in a closed container in the presence of anhydrous aluminum chloride.

of anhydrous aluminum chloride, said aluminum chloride being present in amount between .25 and 5 pounds per 100 pounds of titanium sponge.

References Cited in the file of this patent UNITED STATES PATENTS Kroll June 25, 1940 Singleton Oct. 9, 1956 7 4 OTHER REFERENCES Thorpe: Dictionary of Applied Chemistry, vol. 1, 1916. Pages 113, 114.

Mellor: A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. V, 1946. Pages 316-318. 

1. A METHOD FOR STORING TITANIUM METAL SPONGE WHICH CONTAINS MAGNESIUM CHLORIDE IMPURITY WHICH COMPRISES STORING SAID SPONGE IN A CLOSED CONTAINER IN AN ATMOSPHERE CONDITIONED BY THE PRESENCE OF ALUMINUM CHLORIDE. 